BaseTools/Plugin: Update HostBasedUnitTestRunner to support Linux

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2513

Update HostBasedUnitTestRunner plugin to support the Linux environment
and remove any Windows only logic.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Sean Brogan <sean.brogan@microsoft.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Plugin/HostBasedUnitTestRunner/HostBasedUnitTestRunner_plug_in.yaml

@@ -6,7 +6,7 @@
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 ##
 {
-  "scope": "host-test-win",
-  "name": "Windows Host-Based Unit Test Runner",
+  "scope": "host-based-test",
+  "name": "Host-Based Unit Test Runner",
   "module": "HostBasedUnitTestRunner"
 }